1. Technical Field
The present invention relates to implantable medical devices. More particularly, the present invention relates to an implantable medical device that is adapted to conform to the contour of an implantation site and/or to flex in compliance with movement at such implantation site.
2. Description of the Prior Art
Certain medical devices, such as pulse generators, including cardiac pacemakers and defibrillators, are implanted within a patient's body to monitor patient conditions and/or to administer cardiac arrhythmia therapy as necessary. Advances in microelectronic technology have allowed the manufacture of implantable medical devices that are increasingly sophisticated in their ability to diagnose, counteract, and report critical patient events, such as cardiac arrhythmia.
Prior art implantable defibrillators typically have been relatively large, such that it was necessary to implant the device in the patient's abdominal cavity. Such implantation requires somewhat complex and time consuming surgery and sometimes results in patient discomfort.
K. Anderson, T. Adams, M. Kroll, Defibrillation Pulse Generator, U.S. Pat. No. 5,241,960 (7 Sep., 1993) discloses a pulse generator adapted for implantation in the pectoral region of a patient's body. The device is sealed in a housing structure that has a contoured periphery and that is constructed of a biocompatible material. The device and housing are smaller in size than conventional defibrillators, and the device therefore delivers lower output voltage. However, the proximity of the device to the patient's heart, i.e. in the patient's pectoral muscle region, is thought to allow the device to deliver a more effective shock to the patient's heart than conventional defibrillators.
Although the form factor of implantable medical devices is decreasing (e.g. Anderson et al, discussed above), the implantation and siting of such devices within the human body is still problematic for at least the following reasons: the bulk of such devices displaces the patient's flesh, thereby creating a skin dislocation that is both unsightly and that may protrude sufficiently from the otherwise continuous surface of the patient's skin to expose the device in such way that may be subjected to impact that can damage the device; situating such devices within the patient's body, rather than under the surface of the patient's skin may make access to the device for installation, service, or replacement an unnecessarily invasive surgical procedure that is expensive, and both stressful and painful to the patient; and because such devices are fashioned as packaged electronic assemblies without substantial regard to the contour of or flexion within or about the patient's body, they may cause patient discomfort.
Although it is known to reduce device volume and weight, such that low profile implantable devices may be made, such devices are packaged as rigid assemblies that do not conform to, or comply with, the patient's body. Thus, while smaller devices are produced, such devices may still be somewhat obtrusive and uncomfortable, and may interfere with the patient's normal day-to-day activities. Additionally, there is a possibility that the device will irritate the implantation site, resulting in medical complications. Further, in the case of a pulse generator, interruption to device operation, for example if the device is damaged, can have dire consequences for the patient.
Accordingly, improvements must still be made in fitting implantable devices to the patient's body.